1. Field of Invention
This invention relates to fluid flow sensoring devices, specifically to such devices in which the fluid is measured by the deflection or movement of an object.
2. Background of the Invention
This invention relates to wind and fluid flow sensors, both direction and velocity. The wind sensors come in several basic forms including cup and vane, sonic anemometer, hot wire anemometer and diode type anemometer.
The cup and vane anemometers (U.S. Pat. No. 4,078,426, Casani, March 1978) are by far the most prevalent and can be seen at most airports, atmospheric weather stations and at other agencies interested in measuring wind speed and direction. The cup refers to (typically) three cups spread over 120 degree angles on a horizontal plane. The cups are attached to radially positioned rods that attach to the cup at one end and to a central hub on the other end. The center of the hub is designed in such a way as to allow smooth rotational movement along the vertical axis. In this way the cups will respond to air movement in the horizontal plane. A speed sensor or tachometer is attached to the hub in such a way as to measure to amount of rotation over a specified amount of time. This rotational movement relates to the speed of the impinging air currents and thus to wind speed. One of the drawbacks of this type of anemometer is that the inertia of the mechanical mechanism must be overcome before meaningful measurements can be made. Also, this style of anemometer is not conducive to measuring gusts, again because of the inertia. The Vane refers to an arrow like device that is attached at its center of gravity to a rotational sensor to measure angular deflection from (typically) North. In this way a measurement of the direction of the impinging wind currents can be measured and therefore the wind direction can be determined. A drawback of this type of wind sensor is found in the overshoot and oscillations that occur during changes in wind direction. Also, these sensors display a wind direction even when the wind is not blowing.
Sonic anemometers are a class of instruments that are typically used by research and other scientific concerns. These systems use the changes in the speed of sound as measured over a finite path by (typically) ultrasonic transducers (U.S. Pat. No. 4,320,666, Redding, March/1982). These systems require computers and sophisticated software to measure the speed of sound over several pathways to determine wind velocity and direction. These instruments overcome the failings of the more prevalent cup and vane systems but cost considerably more to purchase and maintain. Also, the vortices shed by the physical structures necessary to hold the transducers rigidly in place cause uncertainties in the measurements.
Hot wire anemometers (U.S. Pat. No. 4,011,756, Lemos, March/1977) consist of several hot wires placed typically at 90 degree intervals in front of appropriately placed shields to measure wind velocity and direction. The amount of air moving across a wire (typically NiChrome) set to a stable temperature, will cause a change in amperage necessary to maintain that temperature proportional to the wind speed. This system uses several sensors to measure the amount of air movement from various angles and therefore interpret the wind speed and direction. These systems require a good deal of power to operate properly and are insensitive to gust conditions. The software and hardware requirements are substantial resulting in high cost for procurement as well as maintenance.
Diode type anemometers (U.S. Pat. No. 4,487,063, Hopper, December/1984) use the same principles of the hot wire systems to determine wind speed and direction. They also suffer from the same drawbacks. Their advantage is in a more robust physical construction allowing their use in aerospace applications and other high vibration venues.
Van Cauwenberghe in U.S. Pat. No. 4,631,958 (1986) uses a sphere attached to a shaft. When the “wind force” moves the shaft, electromagnetic or optical sensors detect the deflection from the neutral position. Signals from the sensors are then computed using a formula to eventually display a wind speed and direction. Also, an actuator is used in the operation of the shaft. This causes excess maintenance and raises the cost of the device.
Gerardi in U.S. Pat. No. 5,117,687 (1992) also uses a sphere attached atop a shaft. The system also uses an array of strain gauges. The excessive use of strain gauges contributes to the overall complexity of the design.
Motycka in U.S. Pat. No. 4,631,959 (1986) employs a pivotally mounted shaft with a drag element attached to the shaft. Placed on the shaft is a ferrite block. Electromagnets are mounted orthogonally on the shaft, adjacent to the ferrite block. Changes in velocity of fluid are detected by a change in voltage across the electromagnets. This voltage is then computed in a micro-processor. Since electromagnets and ferrite are placed on the pivotal shaft, complexity is added to the design and computation of the fluid velocity.
Zysko in U.S. Pat. No. 6,370,949 (2002) also uses a shaft that is to be deflected by a fluid, however, he uses two pairs of sensors to detect the movement of the shaft. This system is only practical at high fluid velocities and could not accurately detect a fluid moving at a realitivley slow speed.
Lake in U.S. Pat. No. H1,688 (1997) employs a shaft as well but uses surface protrusions mounted in a spiral pattern on the shaft to assist in deflection. This system uses four sensors to measure deflection caused by the fluid. Also, a wire mesh, with square grid is used on the surface that is to be deflected. This adds unnecessary complexity to the design.
The fluid flow and direction sensor also has applications in measuring a liquid fluid flow such as but not limited to water. If the Fluid Flow Direction and Velocity Sensor were to be completely inverted. In this situation, the deflection cylinder would be realitivley pointing down. The bottom part of the deflection cylinder would be inserted into the liquid type fluid and detections of the fluid characteristics could be made in much the same manner it would if detecting a gaseous fluid.
In conclusion, we are not aware of any other invention formerly developed in either the detection of gaseous and/or liquid fluid that has our simple design, grade of accuracy, as well as cost efficiency. All of these we have incorporated into our Fluid Flow Direction and Velocity Sensor.